Ionization and dissociation of cyclic ethers and thioethers by electron‐impact. A comparison between 1,3‐dioxolane, 1,3‐dithiolane and 1,3‐oxathiolane

The various modes of fragmentation of 1,3‐dithiolane and 1,3‐oxathiolane under electron‐impact have been discussed on the basis of the variation of their mass spectra with electron energy, the high resolution analysis and the AP's of the main ions. They are shown to be similar in both compounds, but considerably different from those of 1,3 dioxolane. From the AP of the [C 2 H 5 S] + ion in 1,3‐dithiolane, a heat of formation of 63 kcal/mol for the free radical CHS is obtained.